Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Need help - What to do with 2 amplifier outputs into 1 speaker?

Status
Not open for further replies.

audioguru

Well-Known Member
Most Helpful Member
Is this what you are suggesting doing?
No.
The 330 ohm resistors and 3.3uF capacitors are supposed to feed the low impedance input volume control of the development amplifier that drives the speaker.
The toy should have an 8 ohm to 22 ohm resistor replacing the speaker.

EDIT: All amplifiers have an output that goes high and low. A bridged amplifier has two amplifiers, one feeds one wire of the speaker and the other feeds the opposite signal to the other wire of the speaker so that the voltage swing across the speaker is almost doubled which almost doubles the current which increases the power at the speaker almost 4 times.
 
Last edited:

Nigel Goodwin

Super Moderator
Most Helpful Member
As an open collector class D amp, the toy is essentially sending a pulsed low/high impedance signal, so it needs Vcc on the other end of the speaker to pull current.

Assuming it's an open-collector output, you would need a pull-up resistor to make it work, the 22 ohm mentioned earlier would be fine.

The ISD2100, being bridged, is sending (I think) a waveform that is driven alternatively high and low. Does the fact that one is an open collector and one a totem pole type of configuration create a conflict of some kind?

No 'conflict', an open-collector output (which we weren't ever told about), would simply require a pull-up resistor.

The class-D bridged output 'should' have a suitable low-pass filter if you're feeding an external amp.

Is this what you are suggesting doing?
toy2.png

Personally I'd prefer an external amp (use 10K 05 5K resistors, and simply replace the silly 500 ohm pot on the development board), the 330 ohms in this diagram mean you're losing most of the output signal in the resistors.
 
Status
Not open for further replies.

Latest threads

Top